My Adult Son Was Working On His Car Yesterday In

My adult son was working on his car yesterday in Bakersfield CA and started at 5:00am because it has been so hot. He was feeling fine when he started. He was under the car doing wiring on his back looking up and getting up and down. At about 7:30 he started feeling dizzy and nauseous. He did not throw up but just felt nauseous. His wife took his blood pressure and it was 105/70 which is low for him and his pulse was 50 approx. his oxygen was 94-95. He drank Gatorade and water. Later he was able to eat and kept it down and gradually started feeling better but his blood pressure only went up to 117/70 -pulse 60. His blood pressure is still low today. 105/70. He feels ok but his blood pressure is still lower than usual for him. Plans on going to doctor tomorrow. Should he check on it sooner. No chest pains or clammy sweating.